There has been a fuel fill opening structure of a capless type, which is provided in a fuel fill opening of a filler pipe. For example, in Patent Literature 1, a fuel fill opening structure is described, which includes a closing flap for opening or closing a fuel fill opening, a housing for covering a periphery of the fuel fill opening, and drain openings which are drilled upstream of the closing flap of the housing. With the fuel fill opening structure, dust and the like accumulated around the fuel fill opening are discharged outside through the drain openings and condensation inside is prevented.
The fuel fill opening structure described in Patent Literature 1 further includes, in the housing, a guide pipe which is movable along an insertion and removal direction of a fuel gun, a spring which biases the guide pipe toward a direction away from the fuel fill opening, and a packing mounted to an outer peripheral surface of the guide pipe.
According to the fuel fill opening structure of Patent Literature 1, normally when the fuel gun is not being inserted, the guide pipe and the packing are biased toward the direction away from the fuel fill opening by a biasing force of the spring to open the drain openings. Meanwhile, at the time of fueling, when the guide pipe is pushed by the fuel gun, the guide pipe and the packing are moved toward the fuel fill opening against the biasing force of the spring, to close the drain openings. This prevents vapor of fuel from being discharged outside at the time of fueling and prevents air (outside air) through the drain openings.